1. Field of the Invention
The present invention relates to a data communication apparatus and method, and a storage medium capable of being read by a computer. More particularly, the invention relates to a technique of drawing, in a network including a plurality of information supply sources and at least one display device, display information possessed by each of the information supply sources on the at least one display device.
2. Description of the Related Art
Currently, various associations have started their activities for realizing a home network where AV (audio visual) apparatuses and a digital television receiver (hereinafter abbreviated as a. “digital TV”) in a home are interconnected. For example, an association called the 1394 TA (Trade Association) is planning specifications for transport layers based on the IEEE (Institute of Electrical and Electronics Engineers, Inc.) 1394-1995 Standards in order to interconnect a plurality of AV apparatuses including a digital TV with a common digital interface.
Recently, mainly Western countries intend to put digital television broadcasting to practical use. Digital television broadcasting has a capability of simultaneously transferring a plurality of programs with the same bandwidth as the conventional analog TV broadcasting bandwidth.
Particularly, digital television broadcasting can perform broadcasting using digital data. Hence, it is possible to broadcast still images, representing EPGs (electronic programming guides), commercial information, weather information, stock information and the like, together with digital image information and digital sound information. Such digital television broadcasting containing digital information is transferred to and displayed on each digital TV connected to a home network via a set-top box or the like.
It is considered that in a future home network, each display device, such as a digital TV or the like, is connected not only to a dedicated set-top box, but also to other AV apparatuses via a common digital interface.
In such a case, the display device must have the function of displaying display information (hereinafter termed an OSD (on-screen display)) possessed by each AV apparatus on the same picture surface. Particularly when a plurality of AV apparatuses share a single display device, there is the possibility that an OSD (such as a still image or a graphic image) of each AV apparatus simultaneously provides the display device with a request to draw an image during a certain time period. In such a case, the display device must display a plurality of OSDs on the display picture surface so that they overlap with each other as little as possible, or overlap with each other in a state of not causing any problems.
However, since OSDs of respective AV apparatuses are usually transmitted irrespective of layout on the display picture surface of the display device, the display device must process how to layout a plurality of OSDs on the display picture surface. Such a configuration causes a very large burden on the display device, and is not efficient.